RCM can image living tissue from mammary whole organ culture (WOC). Mammary glands from mice primed with an E&P pellet were either whole mounted immediately (uncultured) (A) or exposed to culture in IPAH supplemented media immediately (B-C). Other glands were put into IPAH culture after RCM imaging which was accomplished by injection with either PBS (D-F), 1% acetic acid (G-I), 3% acetic acid (J-L), or 5% acetic acid (M-O). Pre-WOC RCM images (D, G, J, M) display examples of terminal end buds which can be compared to the whole mount (WM) image (A). Alveolar development in the glands can be compared in post-WOC WM (B, E, H, K, N) and H&E (C, F, I, L, O) images. Arrowhead: terminal end bud, arrows: alveolar development, *: lymph node. Magnifications are as indicated.